1. Technical Field
This invention relates to hand tools, specifically to such tools which are used for tightening and loosening elongated hex-head nuts (wing knobs) for vertical plan filing clamps as manufactured by Plan Hold Corp., Stacor Corp., and Safco Corp.
2. Description of Prior Art
Architects, engineers, designers, and draftspersons use vertical plan filing clamps, which are also called stick files, to hold together and hang several full size plan drawings. The clamping mechanisms for these vertical plan files are adjusted by two to three elongated hex-head nuts (wing knobs). The elongated hex-head nut (wing knob) is tapered from top to bottom, such that the top is smaller than the bottom. The nut (knob) transitions to a round shoulder at its base. The shoulder diameter is smaller than the width of the nut (knob). As the torque on these nuts (knobs) is increased, the clamping force on the group of drawings is also increased. The clamp is designed to hold up to one hundred drawings and the nut (knob) is intended to be tightened and loosened with one's bare hands.
When more than thirty drawings are to be held by the file clamp, the required nut (knob) torque to hold the drawings in place is greater than the available torque delivered by an average man. To achieve the minimum torque to adequately clamp thirty or more drawings, many people use a pair of scissors with the handle placed over the nut (knob) to provide leverage. The practice of using scissors usually leads to failure of the scissors and/or physical injury to the individual. A pair of pliers or a crescent wrench has also been used. However, due to the loose fit over the unusual shape of the elongated hex-head nut (wing knob), the chromium finish of the nut is damaged and the corners are stripped. Another disadvantage of using a pliers or a crescent wrench is that these tools are more suited for other uses. Therefore, they rarely remain near the plan filing clamp for future use.
Conventional tools known in the art have been proposed to closely fit the elongated hex-head nut (wing knob). Both of these tools consist of two metal pieces which are welded together. The first is cut with an acetylene gas torch from flat stock carbon steel with a steel rod welded to its side. The second is a torch cut socket with a t-handle welded to its top. The method of gas torch cutting leaves many burs and sharp edges. Both designs are unattractive and expensive to manufacture.
Other types of tools designed for other uses maybe used for tightening and loosening the elongated hex-head nut (wing knob), such as U.S. Pat. Nos. 2,984,135 by Collett; D329,178 by Ackerman; and D274,404 by Adler; however, these designs damage the elongated hex-head nut (wing knob) because they do not closely fit the unique shape of the nut (knob). Moreover, they consist of more than one piece and are expensive to manufacture.
Occasionally, the plastic version of the elongated hex-head nut (wing knob) breaks due to over torquing leaving an exposed bare 5/16" common hex-head nut. None of the above tools satisfactory fit the 5/16" nut; therefor, a second tool is required to loosen this nut.